The present invention relates to an image correction apparatus that performs image correction to an image defect included in image data, that is, a portion where correction is necessary. More specifically, the invention relates to an image correction apparatus that corrects an image defect caused by a defect such as a scratch and dust on a film image read out photoelectrically by using a film scanner and the like.
In recent years, a new technology has been introduced and this is a printer that relies upon digital exposure. Briefly, an image recorded on a film is read photoelectrically, converted to digital signals and subjected to various image processing operations to produce image data for recording purposes; recording light that has been modulated in accordance with the image data is used to scan and expose a photosensitive material to record a latent image, which is subsequently developed to produce a finished print. The printer operating on this principle has been commercialized as a digital photoprinter.
In the digital photoprinter, the film is read photoelectrically and subjected to image (signal) processing for gradation correction or the like to thereby determine exposing conditions. Hence, by image processing, editing of a print image including composition of a plurality of images into one composite image or division of a single image into more than one image, and various image processing operations including color/density adjustment, edge enhancement and the like can be performed freely. Thus, print images can be output after processing has been done in accordance with a specific use. Further, the image data of the print images can be supplied into a computer or the like and stored in recording media such as a floppy disk.
Further, the digital photoprinter is capable of outputting prints of higher image quality which are excellent in the resolution, color/density reproducibility and the like as compared to prints by means of the conventional direct exposure.
Having these features, the digital photoprinter is basically composed of an image input machine having a scanner that reads an image on a film photoelectrically and converts to image data and an image processing apparatus that subjects the image data to processing (image processing) to determine exposing conditions thereby producing image data for recording purposes as well as an image output machine (a printer) that scan exposes a photosensitive material in accordance with the image data output for recording purposes, and performs development and other necessary processing on the exposed material to produce a print.
In the scanner, reading light emitted from a light source is allowed to be incident on the film, from which projected light bearing the image recorded on the film is produced and focused by an imaging lens to form a sharp image on an image sensor such as a CCD sensor; the image is then read by photoelectric conversion and sent to the image processing apparatus as image data of the image on the film (i.e., image data signals) after being optionally subjected to various image processing operations. In the scanner, the carrier mounted on the scanner feeds the film frame by frame whereby the image photographed in each frame of the film is sequentially read one by one.
The image processing apparatus sets image processing conditions for subjecting the image data to color balance adjustment, contrast compensation (gradation processing), brightness correction and chroma correction, and optionally each correction for transverse chromatic aberration, distortion and color shift, and electronic scale conversion, optionally followed by sharpness processing and dodging processing. Image processing as determined by the thus set conditions is performed on the image data and the resulting image data for image recording (i.e., exposing conditions) are sent to the printer.
In the printer, if it is of a type that relies upon exposure by scanning with an optical beam, the latter is modulated in accordance with the image data sent from the image processing apparatus and deflected in a main scanning direction as the photosensitive material is transported in an auxiliary scanning direction perpendicular to the main scanning direction, whereby a latent image is formed as the result of exposure (printing) of the photosensitive material with the image bearing optical beam. Development and other processing as determined by the photosensitive material are then performed to produce a print (photograph) reproducing the image that was recorded on the film.
Incidentally, the print output from the digital photoprinter may include a fine image defect on an actual read image due to a defect physically existing on a frame of the film, for example, a scratch on the film and dust attached to the film. When the reading light emitted from the light source is allowed to be incident on the film to produce projected light bearing the image recorded on the film, if the image of the scratch on the frame of the film or the image of the dust attached to the film is also included in the projected light bearing the image together with the image recorded in the frame, the scratch or dust is also imaged thus causing this defect. The image defect of this kind, that is, the image defect due to the scratch, dust and the like on the film have a problem that the image quality is reduced.
Therefore, Japanese Patent No. 2559970 proposes a method for compensating adverse effects of defects caused in a recording medium such as a film. According to the method adopted therein, infrared ray is used to detect a defect such as a scratch on the film and a level of the defect is determined from the energy distribution intensity of the infrared ray.
However, this method is not sufficient for detecting the image defect caused by the scratch on the film or the dust attached to the film during film scanning so as to efficiently correct the defect in a digital manner.
Alternatively, in the case where the red-eye of a subject person which sometimes occurs in the subject image photographed with a strobe flash, is corrected as the image defect, the method applied is not sufficient for efficiently detecting the red-eye to correct it efficiently in a digital manner. Particularly, when a plurality of subject persons are photographed such as in a group photograph, it is difficult to correct the red-eye phenomenon of all the subject persons efficiently.
On the other hand, it is difficult for an operator to detect the defect such as the scratch and dust on the image one by one with good accuracy while looking at the image displayed on an image display monitor, because the defect on the image is fine. Thus, missing of the detection occurs many times. This also makes the operator to perform a troublesome work.
This kind of problem is not limited to the case where an image recorded on a film is read by the scanner to provide image data. The problem of the image defect included in the image data also occurs in the case where a print is output from image data recorded in a recording medium such as a floppy disk, a PC card, an MO disk (a magneto-optical disk) or the like. For example, in the image photographed by a digital still camera, the image defect due to a defect of an image pickup element is recorded. Thus, the defect to be corrected occurs on the image.